For an even smoother soup, use an immersion blender to partially or fully puree the soup after cooking. If pureeing, reserve some of the cooked peas and kohlrabi to add back in for texture. If fresh peas are unavailable, frozen peas work perfectly well. Add them directly from frozen; no need to thaw. The soup can be made a day ahead and stored in the refrigerator. The flavors will meld beautifully. Consider adding a squeeze of fresh lemon juice or a swirl of yogurt or crème fraîche just before serving for added brightness and richness.